In recent years, fine patterns of a semiconductor device are often formed by sidewall transfer process. For example, word lines of a semiconductor storage device such as a NAND memory are formed by the sidewall transfer process for downscaling purposes in many cases. However, when the word lines are formed by the sidewall transfer process, the reduction of the line width and the space width of the word lines makes it difficult to form pad portions (hook-up portions), which are used to dispose contact plugs on the word lines. The reason is that the reduction of these widths makes it difficult, when lithography for processing the pad portions is performed, to perform the alignment in lithography for dividing the pad portions and cutting the word lines from the pad portions. Therefore, a method that can process the pad portions simply and accurately is demanded.